Synthesis and characterization of activated carbon monolith from African locust bean pods and polystyrene resin

Abstract

ABSTRACT Activated carbon monoliths (ACMs) are single-piece, three-dimensional (3D) hierarchical porous structures with good permeability, high stability, and swift mass transfer features. Production of activated carbon monoliths from biomass has been identified as promising and sustainable for process development. In this study, ACM was synthesised from African locust bean pods and polystyrene resin. The pods were chemically activated using potassium hydroxide and then carbonised in a locally fabricated auto-thermal biomass-powered reactor for 100 minutes. The activated carbon was then hand-mixed with an organic binder, expanded polystyrene resin, and the product was thermally cured to form the ACM. The ACM was then characterised to determine its properties. Elemental determination revealed the ACM was mostly composed of carbon (63%), potassium (18%), oxygen (4%), and a host of other metals. SEM micrographs showed that the ACM’s surface is composed of irregular or heterogeneous-sized carbon materials firmly held by the resin with well-developed visible micropores. Some of the functional groups inherent in the ACM include hydroxyl, alkene, carbonyl, and alkyne. The ACM has a BET surface area of 237 m2/g, a pore diameter of 2.86 nm, and a Young modulus of 1.064 MPa. The synthesised ACM can be utilised as an adsorbent for pollution control, as a catalyst, and for electrochemical applications.